Miss from 1k-3k RPM

[chevy42083]

Ok, so I just got my truck back up and running after a couple years, but i'm having 2 issues.

First of all, I don't have a battery for it... it borrows my daily's for a couple hours at a time... so the computer gets reset each time.

At start up, it takes wrapping on the gas a couple times to get it to fire, and keep it running. It'll still die... but after a couple times, it'll be able to idle. Then it runs close to how it always did till warmed up, then it's perfect. I'm fairly sure this is being caused by the lack of battery... but still isn't "right".

I took it for a drive on sunday to put some air in the tires. Waited for it to warm up, and drove the mile or so. Ran perfect. On starting it back up for the return trip, it ran HORRIBLE. Idles smooth, but at anything between 1k and 3k it has a horrible miss... like a BIG stutter... feels like the motor is going totally dead for a second.
Above 3, it runs fine (at cruising constant RPM, hard accelerating, and WOT)

One issue... intake tube was sitting ON the radiator hose, and was VERY hot once I got back to the shop. Could this cause the problem? Did it sit there and soak up the heat while filling tires, and start this problem?

Going to fix this anyways... but anything else I should look over?

[BLOWNDFIZ]

Sorry to sound like Mr. Obvious here, but I'd honestly just get a battery for it and see if that fixes your problem. I mean there is no use wasting your time chasing a "problem" if you already think it might just be a battery issue.

Case in point my dad owns an auto restoration business. He finished up a 70 Z28 for a guy in South Carolina, and after taking delivery the guy didn't drive it very often because each time he did he had to use a jumper pack to start it and it would barely run. He thought it was my dad's fault so dad flew down to SC only to find out the battery was indeed junk. So the customer ended up paying for all of my dads expenses and a new battery.:doh:

Moral to the story, always rule out the easiest possible solution first.

[chevy42083]

I could see that being the start-up issue... just not sure how that could effect the miss between 1k and 3k rpm. The battery it borrows IS in good shape... I just don't know how the OBDI LT1 PCMs react to being "unplugged" between runs.
But you are right.
I just don't get a chance to mess with it... so I wanted to have a "list" of things to attack. Instead of getting a battery, not fixing it, and having to wait a week to look at it again.

I was kinda wondering if a AIT sensor reading high, or a really hot MAF might cause these symptons.

[BLOWNDFIZ]

I could see that being the start-up issue... just not sure how that could effect the miss between 1k and 3k rpm. The battery it borrows IS in good shape... I just don't know how the OBDI LT1 PCMs react to being "unplugged" between runs.
But you are right.
I just don't get a chance to mess with it... so I wanted to have a "list" of things to attack. Instead of getting a battery, not fixing it, and having to wait a week to look at it again.

I was kinda wondering if a AIT sensor reading high, or a really hot MAF might cause these symptons.

I would not think the IAT sensor would be the problem. I know before I had the aftercooler would see some seriously high inlet air temps and it ran fine. You might get some MAF sensor cleaner and spray the MAF. Also, check all of the plug wires and coil wire. My DD when I bought it had a terrible mis at part throttle under a load and it turned out the coil wire was litterally held together by a single strand. If you have headers and use the metal boots on the plugs they might be arching to the header tubes. I had that happen to me also. You could hear the arching at idle. Oh I also had a broken spark plug once that caused a bad mis. I was thinking the worst (opti) and ended up buying a new coil, wires, and plugs. I started the project by removing the plugs and low and behold one of them was broken. Replaced it, ran like a champ!

I keep thinking of more....Replace the fuel filter and check fuel pressure. Since you don't drive it that much, the fuel filter could be partially clogged, or the pump may have a hard time priming. An easiy check for this is to cycle the key 3-4 times before you start the vehicle. That way you can ensure pressure at the injectors. Again just thinking off the top of my head.

Just some easy things to rule out.

[MEAN LT1]

Im asssuming your running SD? or you still running a maf on your truck. Does this hiccup only happen during light loads on the motor or heavy?.Are you getting any ses lights to show up?.

[chevy42083]

Fuel filter is new.
Fuel is new.
Plugs are new.
It does run a MAF.
happens at light load and heavy load (didn't notice on decel/no load, and can't do WOT that low w/ automatic)

On the trip TO the store... it ran fine... no matter what load or RPM. It was just the return trip that had the stutter.

I have tried priming the pump several times, and still won't run right away at start-up. It fires quickly... then just sputters out unless I wrap on the throttle (a steady foot will still result in the RPMs slowly dropping and dieing)

SES is a tough subject. Part of the swap was never done right, and it always has a light. Getting it hooked up to a scanner is on the short list now (it had run for years with no issues before).

Ok, so list of what to do...
MAF cleaner.
The plug wires are not that old, and show no wear. I'll pull them all off, and press back onto plugs to ensure tight fit.
Coil wire... old... I'll check it out... I might have some spare cut to fit and plug ends sitting around.

Now that I mention the startup problems needing rapid throttle jabbing and not a steady throttle... I'm wondering about TPS. I think I may have an extra sitting around to try.

Video of the startup is in my thread in this section titles "waking stored engine" if that may give some hints to that problem. It's the stutter that really has me worried... but they may be related.

[MEAN LT1]

Kinda hard to tell at this this point. If the swap was never done right its kinda hard to chase down the problem. Not trying to be a dick or anything but why dont you go through the wireing and at least get the ses light and aldl to work right. If the ses light was working the answer could e right in front your face instead of guessing. :cool:

[JoeliusZ28]

when my car did this it was spark plug wires.

here's a video if you have the same thing:
http://www.youtube.com/watch?v=aVFakrFLVV0